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Journal articles on the topic 'Bond polarization'

Author: Grafiati

Published: 4 June 2021

Last updated: 12 February 2022

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1

Gudat, D. "A very peculiar family of N-heterocyclic phosphines: unusual structures and the unique reactivity of 1,3,2-diazaphospholenes." Dalton Transactions 45, no. 14 (2016): 5896–907. http://dx.doi.org/10.1039/c6dt00085a.

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2

Sun, Yu, Zi-Lin Yuan, Qian-Ze Li, Cai-Xin Zhang, Ke-Qiu Chen, and Li-Ming Tang. "Electrically controlled valley polarization in 2D buckled honeycomb structures." Modern Physics Letters B 35, no. 25 (August 3, 2021): 2150390. http://dx.doi.org/10.1142/s0217984921503905.

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Generating and manipulating valley polarization in a controlled method is significant. The inherently broken centrosymmetry of the buckled honeycomb structures gives it both ferroelectricity and valley degree of freedom, which provides an opportunity to realize electrically controlled valley polarization. In the first step, we explored the origin of buckling. The hexagonal structure is polar due to buckling of the surface, but the degree of buckling and the energy barrier to switching electric polarization are determined not solely by the chemical composition. We combined the electronegativity difference, bond length and the distribution of charge density to describe quantificationally the polarity of chemical bonds. It shows the characteristics of relatively long bond-length but relatively small electronegativity-difference. For exploring the ferroelectricity of buckling structures and the behavior of ferroelectric (FE) control of the valley degree of freedom, the [Formula: see text]-GaP is used as a model system to elucidate the strain effect on FE behavior and the magnetic proximity effect on the polarization and switching of valley. We found that the spontaneous polarization is positively correlated with the electronegativity difference within a certain range, and the compression strain can effectively manipulate spontaneous polarization and switch barrier. A combination of the magnetic proximity effect and the inversion of electric polarization can generate and switch valley polarization effectively.

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3

Rodina, A. V., A. A. Golovatenko, E. V. Shornikova, D. R. Yakovlev, and Al L. Efros. "Dangling bond spins controlling recombination dynamics of excitons in colloidal nanocrystals and nanoplatelets." Физика и техника полупроводников 52, no. 5 (2018): 500. http://dx.doi.org/10.21883/ftp.2018.05.45844.33.

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AbstractWe show theoretically that spins of dangling bonds (DBSs) at the surface of colloidal nanostructures can be responsible for the dark exciton radiative recombination governing low temperature photoluminecence. The DBS-assisted dark exciton recombination is efficient when all spins are randomly oriented. The DBS polarization caused by external magnetic field or by the formation of the dangling bond magnetic polaron (DBMP) at low temperatures suppresses the DBS-assisted recombination. The temperature or magnetic field control on the DBS-polarization allows to detect experimentally the presence of DBS and DBS-assisted recombination in CdSe nanocrystals and 2D nanoplatelets.

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4

Xiao, Xiao Hong, and Shi Chun Li. "Chemical Bonds Properties and Spontaneous Polarization of Orthogonal SrBi₂Ta₂O₉ Crystals." Materials Science Forum 848 (March 2016): 688–95. http://dx.doi.org/10.4028/www.scientific.net/msf.848.688.

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The bonds structure, atomic coordination situation and local cluster structure in SrBi2Ta2O9 were analyzed by means of the Atomic Environment Calculation (AEC), and then the SrBi2Ta2O9 crystal was decomposed into 20 pseudo-binary crystals with the crystal decomposition method. The chemical bonds properties, such as effective valence electron density and iconicity of the individual bond were calculated by the dielectric chemical bonds theory. And the correlation between chemical bonds properties and spontaneous polarization of the bismuth layered ferroelectrics was established. Finally, the spontaneous polarization in ferroelectric SrBi2Ta2O9 and other relevant ferroelectrics were calculated, which are in good agreement with the experimental values and other theoretical calculated values.

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5

Sun, Chang Q. "Unprecedented O:⇔:O compression and H↔H fragilization in Lewis solutions." Physical Chemistry Chemical Physics 21, no. 5 (2019): 2234–50. http://dx.doi.org/10.1039/c8cp06910g.

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Charge injection in terms of protons, lone pairs, cations and anions by acid and base solvation mediates the HB network and properties of Lewis solutions through H↔H fragilization, O:⇔:O compression and polarization, ionic polarization and hydrating H₂O dipolar screen shielding, anion–anion repulsion, compressed solvent H–O bond elongation and undercoordinated solute H–O bond contraction.

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6

Levine, Daniel S., and Martin Head-Gordon. "Energy decomposition analysis of single bonds within Kohn–Sham density functional theory." Proceedings of the National Academy of Sciences 114, no. 48 (November 20, 2017): 12649–56. http://dx.doi.org/10.1073/pnas.1715763114.

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An energy decomposition analysis (EDA) for single chemical bonds is presented within the framework of Kohn–Sham density functional theory based on spin projection equations that are exact within wave function theory. Chemical bond energies can then be understood in terms of stabilization caused by spin-coupling augmented by dispersion, polarization, and charge transfer in competition with destabilizing Pauli repulsions. The EDA reveals distinguishing features of chemical bonds ranging across nonpolar, polar, ionic, and charge-shift bonds. The effect of electron correlation is assessed by comparison with Hartree–Fock results. Substituent effects are illustrated by comparing the C–C bond in ethane against that in bis(diamantane), and dispersion stabilization in the latter is quantified. Finally, three metal–metal bonds in experimentally characterized compounds are examined: a MgI–MgI dimer, the ZnI–ZnI bond in dizincocene, and the Mn–Mn bond in dimanganese decacarbonyl.

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7

Mermer, Adrian, and Przemysław Starynowicz. "Charge-density distribution in potassium dihydrogen phosphoglycolate – a comparison of phosphate and phosphonate groups." Acta Crystallographica Section B Structural Science 68, no. 6 (October 23, 2012): 625–35. http://dx.doi.org/10.1107/s0108768112040724.

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Analysis of the experimental and theoretical charge-density distribution in potassium dihydrogen phosphoglycolate has been performed. The P—O bonds in the phosphate group are more polarized and the P atom is more positively charged than in phosphonate groups. The P—O bonds belong to a transit closed-shell (or polar covalent) class, while the ester C—O bond is a covalent (or shared-shell) bond. The coordination of potassium exerts a small effect on the phosphate group, whereas more pronounced changes, e.g. concerning the ellipticities of the C—O bonds, may be observed. The profiles of Laplacians and ellipticities give more insight in the polarization of the bonds.

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8

Miller, Ian J. "Semiclassical Quantum Mechanics, Bond Delocalization and the Mills - Nixon Effect." Australian Journal of Chemistry 50, no. 8 (1997): 795. http://dx.doi.org/10.1071/c96161.

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Conjugated π electrons in a ring system are described in terms of a transverse wave propagated along the carbon skeleton. Kekule benzene is forbidden because the π electron quantal wave self-interferes. The characteristics of an aromatic system are expressed in terms of the weighted combination of Kekule structures, and resonance energy occurs through combining canonical structures with conservation of momentum. The resonance energy of benzene is calculated as 1·045 times the energy difference between two carbon-carbon single bonds and one double bond, or 162 kJ/mol on one bond energy scheme. Bond localization is due to differences in wave impedance between zones represented by adjacent phase space cells; wave reinforcement occurs in one zone, cancellation in another as a consequence of the directional asymmetry of phase changes of the quantal wave. Quantal wave impedance can be altered by altering the localized potential, and it is proposed that the so-called Mills-Nixon effect arising from the annelation of bicyclic rings occurs because the bicyclic ring better focuses a polarization field. The polarization field arising as a consequence of strain is shown to semiquantitatively account for the bond alternation. The difference between exo and endo bond lengths in tris(bicyclo[2.1.1]hexeno)benzene is calculated to be 7·2 pm, compared with 9 pm as determined experimentally.

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9

Poier, Pier Paolo, and Frank Jensen. "Including implicit solvation in the bond capacity polarization model." Journal of Chemical Physics 151, no. 11 (September 21, 2019): 114118. http://dx.doi.org/10.1063/1.5120873.

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10

Jackson, Mark D. "Multipolar bond-polarization model for ions in crystalline solids." Ferroelectrics 111, no. 1 (November 1990): 49–56. http://dx.doi.org/10.1080/00150199008217600.

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11

Loushin, Sharilyn K., and Clifford E. Dykstra. "Polarization counterpoise corrections to correlated hydrogen bond interaction energies." Journal of Computational Chemistry 8, no. 1 (January 1987): 81–83. http://dx.doi.org/10.1002/jcc.540080110.

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12

Oliveira, Boaz G. "The covalence and infrared spectra of cationic hydrogen bonds and dihydrogen bonds." Journal of Theoretical and Computational Chemistry 13, no. 07 (November 2014): 1450060. http://dx.doi.org/10.1142/s0219633614500606.

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A theoretical study of hydrogen bonds and dihydrogen bonds formed by ethyl cation, hydrocarbons and magnesium hydride is presented with calculations performed at the BHandHLYP/6-31G(d,p) level of theory. The structural results and IR analyses demonstrated great insights, mainly the strengthening and weakness of the CC bond of the ethyl cation and π or pseudo-π bonds, respectively. The interaction strength was measured through the supermolecule as well as by means of additional approaches. The QTAIM calculations were applied to characterize not only the intermolecular interactions but specifically the covalent character in the H + ⋯ π, H + ⋯ pseudo-π and H + ⋯ H contacts. The NBO calculations were useful to interpret the polarization on the CC bond and whether this effect is related with the bond length reduction as well as increase of charge density and frequency shifts.

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13

A, David Stephen, and Shankar M. "Theoretical Charge density Proof of N–N weak bonds of RDX Energetic Molecule." Frontiers in Advanced Materials Research 1, no. 1 (May 30, 2019): 53–71. http://dx.doi.org/10.34256/famr19110.

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The bond topological analysis of Cyclotrimethylene-trinitramine (RDX) energetic molecule has been carried out for the wave function obtained from the ab initio and DFT methods of quantum chemical calculations. The geometrical parameters of all bonds are compared with that of experimental reports. The inclusion of diffuse function in HF basis set levels makes the significant shift of bond critical point towards carbon atoms of C–N bonds. The heteroatomic bond density character is well understood from unequal C-cp and cp-N distances in all C–N bonds. For all the level of calculations, the maximum bond density was found for all N=O bonds, attributes the maximum potential energy V(r). The N–N bond properties are strongly depends upon the equilibrium bond length which clears from charge concentration in shorter N1–N4 bond and charge depletion found in longer N2–N5 and N3–N6 bonding regions. The bond topological analysis of all bonds in RDX molecule resulted that the N–N bond is the weakest among all the other bonds. The weakness of N2–N5 and N3–N6 bonds than N1–N4 bond of RDX has also been analyzed from energy density calculation from various level of theories as an alternate for Laplacian of electron density. From the analysis of CHELPG charges at the MP2 level, the N–N bonds of RDX appears to have a significant ionic nature which attributes strong hyperconjugation effect. The hyperconjugation effect of RDX, due to polarization of N–N bonds, is the additional proof of weak N–N bonds in RDX explosive. The isosurface electrostatic potential shows the electro positive and negative region in the molecule. A large negative potential found at the vicinity of oxygen atoms.

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14

Jin, Hao, Ying Dai, BaiBiao Huang, and M. H. Whangbo. "Ferromagnetism of undoped GaN mediated by through-bond spin polarization between nitrogen dangling bonds." Applied Physics Letters 94, no. 16 (April 20, 2009): 162505. http://dx.doi.org/10.1063/1.3123169.

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15

Yépes, Andrés F., Alirio Palma, Antonio Marchal, Justo Cobo, and Christopher Glidewell. "2-Amino-6-methoxy-4-(4-methylanilino)-5-nitrosopyrimidine and ethylN-[4-(adamantan-1-ylamino)-2-amino-5-nitrosopyrimidin-6-yl]-3-aminopropionate: polarized electronic structures and hydrogen-bonded supramolecular assembly in one and two dimensions." Acta Crystallographica Section C Crystal Structure Communications 68, no. 5 (April 26, 2012): o199—o203. http://dx.doi.org/10.1107/s0108270112017921.

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In both 2-amino-6-methoxy-4-(4-methylanilino)-5-nitrosopyrimidine, C12H13N5O2, (I), and ethylN-[4-(1-adamantylamino)-2-amino-5-nitrosopyrimidin-6-yl]-3-aminopropionate, C19H28N6O3, (II), the nitrosopyrimidine unit is planar and the bond distances provide evidence for significant polarization of the electronic structures. In (II), the ethoxycarbonyl fragment of the molecule is disordered over two sets of sites with occupancies of 0.910 (4) and 0.090 (4). In the molecules of both compounds, there is an intramolecular N—H...O hydrogen bond. The molecules of (I) are linked into a chain of rings by a combination of N—H...O and C—H...O hydrogen bonds, while the molecules of (II) are linked by a two-centre N—H...N hydrogen bond and a three-centre N—H...(N,O) hydrogen bond to form sheets containing four distinct types of ring.

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16

Guo, Yongling, Maolin Bo, Yan Wang, Yonghui Liu, Chang Q. Sun, and Yongli Huang. "Tantalum surface oxidation: Bond relaxation, energy entrapment, and electron polarization." Applied Surface Science 396 (February 2017): 177–84. http://dx.doi.org/10.1016/j.apsusc.2016.11.010.

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17

Sinha, K. P. "Bond polarization mechanism for the superconductivity of doped C60 systems." Solid State Communications 83, no. 4 (July 1992): 291–94. http://dx.doi.org/10.1016/0038-1098(92)90274-d.

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18

LIU, CUI, DONG-XIA ZHAO, and ZHONG-ZHI YANG. "ABEEMσπ FLUCTUATING CHARGE FORCE FIELD APPLIED TO ALANINE DIPEPTIDE AND ALANINE DIPEPTIDE–WATER SYSTEMS." Journal of Theoretical and Computational Chemistry 09, supp01 (January 2010): 77–97. http://dx.doi.org/10.1142/s0219633610005530.

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Atom-bond electronegativity equalization method at σπ level fused into molecular mechanics (ABEEMσπ/MM) divides the bond regions into σ and π bond regions on the basis of previous ABEEM/MM. It may suitably reflect intramolecular and intermolecular interaction and polarization. The fitting function k H-bond in the hydrogen bond (HB) interaction region increases the capability of ABEEMσπ/MM to simulate the hydration. Hydration of alanine dipeptide (AD) in aqueous solution is determined by the intramolecular and intermolecular HBs and the competition among the molecular packing effects. The acceptor molecule in HB complex contains at least one pair of lone pair electrons, sometimes contains π bonds, whose orientations directly effect the orientation of HBs. Therefore, ABEEMσπ/MM has obviously predominance to discuss the AD and AD–water systems, which contain many lone pair electrons, π bonds, and abundant HB nets. Properties of six AD conformers, clusters AD +( H2O )1–4 obtained from ABEEMσπ/MM agree well with the results of experiments, ab initio and other force fields. Structural and dynamical properties of the hydration water molecules have just embodied that the ABEEMσπ/MM gives correct hydration description relative to other force fields.

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19

Mamedov, S., and N. Drichko. "Characterization of 2D As2S3 crystal by Raman spectroscopy." MRS Advances 3, no. 6-7 (2018): 385–90. http://dx.doi.org/10.1557/adv.2018.201.

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AbstractAs2S3 is a semiconductor, which is known as a layer crystal with structure that is very similar to the metal chalcogenides, such as MoS2 and graphite. In such crystalline structure, the molecular unit is extended in two dimensions indefinitely. The unit cell of As2S3 contains two layers with bond length of 2.24A within the layer and 3.56A between the layers. Large difference between interlayer and intralayer bond length corresponds to a significant difference in bond strengths. The weak bonding between layers primarily occurs via van der Waals interactions. Optical phonons in 2D layer crystal As2S3 have been investigated by Raman scattering in temperature range of 4K-270K in two polarizations in the layer plane (ac plane). Our experimental data shows strong polarization dependence of Raman bands in ac plane for internal mode (intra-layer interactions). Additionally, it presents low frequency band, due to the weak inter-layer interaction. The important evidence for the dominance of layer symmetry with very weak interaction between the layers provides understanding of structural motives of As2S3 and may predict optical / electronic properties of similar 2D materials.

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20

Zhou, Wei, Maolin Bo, Yan Wang, Yongli Huang, Can Li, and Chang Q. Sun. "Local bond-electron-energy relaxation of Mo atomic clusters and solid skins." RSC Advances 5, no. 38 (2015): 29663–68. http://dx.doi.org/10.1039/c5ra00112a.

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21

Sun, Yuanwei, Adeel Y. Abid, Congbing Tan, Chuanlai Ren, Mingqiang Li, Ning Li, Pan Chen, et al. "Subunit cell–level measurement of polarization in an individual polar vortex." Science Advances 5, no. 11 (November 2019): eaav4355. http://dx.doi.org/10.1126/sciadv.aav4355.

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Recently, several captivating topological structures of electric dipole moments (e.g., vortex, flux closure) have been reported in ferroelectrics with reduced size/dimensions. However, accurate polarization distribution of these topological ferroelectric structures has never been experimentally obtained. We precisely measure the polarization distribution of an individual ferroelectric vortex in PbTiO3/SrTiO3 superlattices at the subunit cell level by using the atomically resolved integrated differential phase contrast imaging in an aberration-corrected scanning transmission electron microscope. We find, in vortices, that out-of-plane polarization is larger than in-plane polarization, and that downward polarization is larger than upward polarization. The polarization magnitude is closely related to tetragonality. Moreover, the contribution of the Pb─O bond to total polarization is highly inhomogeneous in vortices. Our precise measurement at the subunit cell scale provides a sound foundation for mechanistic understanding of the structure and properties of a ferroelectric vortex and lattice-charge coupling phenomena in these topological ferroelectric structures.

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22

Mishra, Kamal K., Santosh K. Singh, Paulami Ghosh, Debashree Ghosh, and Aloke Das. "The nature of selenium hydrogen bonding: gas phase spectroscopy and quantum chemistry calculations." Physical Chemistry Chemical Physics 19, no. 35 (2017): 24179–87. http://dx.doi.org/10.1039/c7cp05265k.

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Charge transfer interactions, along with electrostatic and polarization interactions, are important for the strength of hydrogen bonding when poorly electronegative atoms act as hydrogen bond acceptors.

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23

Collins, MJ, PM Hatton, and S. Sternhell. "An N.M.R. Investigation of Ground-State Polarization of Some Substituted Aromatic Systems." Australian Journal of Chemistry 45, no. 7 (1992): 1119. http://dx.doi.org/10.1071/ch9921119.

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The previously established n.m.r. method for estimating mobile bond orders was applied to the investigation of ground-state polarization of benzene derivatives with ortho or para pairs of +R/-R substituents, naphthalene and five heteroaromatic systems (furan, thiophen, pyrrole, quinoline and pyrazole). Evidence for significant ground-state polarization which is solvent-independent was found in a number of these systems, especially benzene, pyrrole and pyrazole.

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24

Rösch, Bastian, Thomas Xaver Gentner, Jonathan Eyselein, Alexander Friedrich, Jens Langer, and Sjoerd Harder. "Mg–Mg bond polarization induced by a superbulky β-diketiminate ligand." Chemical Communications 56, no. 77 (2020): 11402–5. http://dx.doi.org/10.1039/d0cc05200k.

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25

Klamt, Andreas, Jens Reinisch, Frank Eckert, Arnim Hellweg, and Michael Diedenhofen. "Polarization charge densities provide a predictive quantification of hydrogen bond energies." Phys. Chem. Chem. Phys. 14, no. 2 (2012): 955–63. http://dx.doi.org/10.1039/c1cp22640a.

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26

Lin, Kang, Xiaochun Gong, Qiying Song, Qinying Ji, Wenbin Zhang, Junyang Ma, Peifen Lu, et al. "Directional bond breaking by polarization-gated two-color ultrashort laser pulses." Journal of Physics B: Atomic, Molecular and Optical Physics 49, no. 2 (December 21, 2015): 025603. http://dx.doi.org/10.1088/0953-4075/49/2/025603.

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27

Bruun, Jesper, Trygve Helgaker, and Frank Jensen *. "A comparison of polarization and bond functions for density functional calculations." Molecular Physics 102, no. 23-24 (December 10, 2004): 2559–62. http://dx.doi.org/10.1080/0026897042000275026.

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28

Gong, Yinyan, Yong Zhou, Huacheng Wu, Danping Wu, Yongli Huang, and Chang Q. Sun. "Raman spectroscopy of alkali halide hydration: hydrogen bond relaxation and polarization." Journal of Raman Spectroscopy 47, no. 11 (June 14, 2016): 1351–59. http://dx.doi.org/10.1002/jrs.4963.

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29

Wright, James S., and V. J. Barclay. "Approaching the exact energy for H2: Bond functions vs polarization functions." Journal of Chemical Physics 86, no. 5 (March 1987): 3054–55. http://dx.doi.org/10.1063/1.452012.

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30

Putintsev, N. M., D. N. Putintsev, A. B. Zinov’eva, and N. V. Stepanova. "The method of bond additivity for the deformation polarization of substances." Russian Journal of Physical Chemistry A 84, no. 4 (January 2010): 624–28. http://dx.doi.org/10.1134/s0036024410040187.

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31

Martin, J. M. L., J. P. Fran�ois, and R. Gijbels. "Combined bond-polarization basis sets for accurate determination of dissociation energies." Theoretica Chimica Acta 76, no. 3 (1989): 195–209. http://dx.doi.org/10.1007/bf00527473.

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32

Li, An Yong, Li Juan Cao, and Hong Bo Ji. "Theoretical study of H bonds of HArF and HF with isoelectronic systems N2, CO, and BF." Canadian Journal of Chemistry 88, no. 4 (April 2010): 352–61. http://dx.doi.org/10.1139/v10-004.

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The H bonds of HArF and HF with N2, CO, and BF were studied at the MP2(full)/6-311++G(2d, 2p) level. The results show that only the complexes WY···HArF (WY = N2, OC) and WY···HF (WY = N2, OC, FB) are stable, the H-bonding WY···HArF leads to contraction of the HAr bond with a concomitant frequency blue shift, but the H-bonding WY···HF causes the HF bond to elongate with a frequency red shift. A quantity P is defined to measure polarization of the HX bond; the H bonding causes the P value of the HX bond (X = Ar, F) to increase. The HX bond length change and frequency shift in the H-bonding WY···HArF and WY···HF are mainly caused by intermolecular hyperconjugation, n(Y) → σ*(HX) (X = Ar, F), where electrostatic interaction has only a small contribution. In HArF, the strong intramolecular hyperconjugation, n(F) → σ*(HAr), can adjust electron density on σ*(HAr); upon formation of H bonding, the HAr stretching frequency blue shift is caused by a decrease of intramolecular hyperconjugation and an increase of the s character of the Ar hybrid in the HAr bond, induced by the intermolecular hyperconjugation. In the H bonds of HF without intramolecular hyperconjugation, the intermolecular hyperconjugation, n(Y) → σ*(HF), leads to a red shift of the HF bond, although there is also large rehybridization.

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33

Wang, Xin, Wei Jiang, Wenshuai Zhu, Hongping Li, Sheng Yin, Yonghui Chang, and Huaming Li. "A simple and cost-effective extractive desulfurization process with novel deep eutectic solvents." RSC Advances 6, no. 36 (2016): 30345–52. http://dx.doi.org/10.1039/c5ra27266a.

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The extractive mechanism contained complex interaction between DESs and sulfur compounds, including CH–π interaction, hydrogen bond effect, polarization of DESs that confirmed by experimental and theoretical method.

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34

Silla, Josué M., and Matheus P. Freitas. "A halogen bond does not dictate the conformational preferences of cis-1,3-disubstituted cyclohexanes." Organic & Biomolecular Chemistry 14, no. 36 (2016): 8610–14. http://dx.doi.org/10.1039/c6ob01635a.

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A halogen bond is unlikely to control the conformation of cis-1,3-disubstituted cyclohexanes. In addition, polarization rather than the σ-hole effect describes this weak interaction more appropriately.

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35

Minton, Timothy K., Gilbert M. Nathanson, and Yuan T. Lee. "Photodissociation of CH2ClCH2I at 308 nm." Laser Chemistry 7, no. 5-6 (January 1, 1987): 297–304. http://dx.doi.org/10.1155/lc.7.297.

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The technique of photofragmentation translational spectroscopy has been used to study the photodissociation of CH2ClCH2I at an excitation wavelength of 308 nm. The exclusive dissociation pathway is C–I bond breakage with formation of CH2ClCH2 and I(2P3/2). The centre-of-mass translational energy distribution of the photofragments reveals that an average of about 50% of the excess energy appears in translation. The angular distribution of dissociation products with respect to the laser polarization indicates that the photodissociation process proceeds via a parallel transition—i.e., the transition moment must be nearly parallel to the C–I bond. Exclusive production of ground state I(2P3/2) with a parallel polarization dependence is unexpected based on the prevailing picture for alkyl iodide photodissociation.

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36

Brinkmann, Andreas, Ulrich Sternberg, Petra H. M. Bovee-Geurts, Isabelle Fernández Fernández, Johan Lugtenburg, Arno P. M. Kentgens, and Willem J. DeGrip. "Insight into the chromophore of rhodopsin and its Meta-II photointermediate by 19F solid-state NMR and chemical shift tensor calculations." Physical Chemistry Chemical Physics 20, no. 48 (2018): 30174–88. http://dx.doi.org/10.1039/c8cp05886e.

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37

Gao, Han, Lingfei Hu, Yanlei Hu, Xiangying Lv, Yan-Bo Wu, and Gang Lu. "Origins of Lewis acid acceleration in nickel-catalysed C–H, C–C and C–O bond cleavage." Catalysis Science & Technology 11, no. 13 (2021): 4417–28. http://dx.doi.org/10.1039/d1cy00660f.

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38

Senthilkumar, Kittusamy, Jon I. Mujika, Kara E. Ranaghan, Frederick R. Manby, Adrian J. Mulholland, and Jeremy N. Harvey. "Analysis of polarization in QM/MM modelling of biologically relevant hydrogen bonds." Journal of The Royal Society Interface 5, suppl_3 (September 2, 2008): 207–16. http://dx.doi.org/10.1098/rsif.2008.0243.focus.

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Combined quantum mechanics/molecular mechanics (QM/MM) methods are increasingly important for the study of chemical reactions and systems in condensed phases. Here, we have tested the accuracy of a density functional theory-based QM/MM implementation (B3LYP/6-311+G(d,p)/CHARMM27) on a set of biologically relevant interactions by comparison with full QM calculations. Intermolecular charge transfer due to hydrogen bond formation is studied to assess the severity of spurious polarization of QM atoms by MM point charges close to the QM/MM boundary. The changes in total electron density and natural bond orbital atomic charges due to hydrogen bond formation in selected complexes obtained at the QM/MM level are compared with full QM results. It is found that charge leakage from the QM atoms to MM atomic point charges close to the QM/MM boundary is not a serious problem, at least with limited basis sets. The results are encouraging in showing that important properties of key biomolecular interactions can be treated well at the QM/MM level employing good-quality levels of QM theory.

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39

Bistoni, Giovanni, Sergio Rampino, Nicola Scafuri, Gianluca Ciancaleoni, Daniele Zuccaccia, Leonardo Belpassi, and Francesco Tarantelli. "How π back-donation quantitatively controls the CO stretching response in classical and non-classical metal carbonyl complexes." Chemical Science 7, no. 2 (2016): 1174–84. http://dx.doi.org/10.1039/c5sc02971f.

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We definitively show that the CO stretching response to metal coordination is driven exclusively by π polarization, which quantitatively correlates with π back-donation and changes in CO bond length and frequency.

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40

Cortés, Edwar, Rodrigo Abonía, Justo Cobo, and Christopher Glidewell. "Hydrogen-bonded sheet structures in methyl 4-(4-chloroanilino)-3-nitrobenzoate and methyl 1-benzyl-2-(4-chlorophenyl)-1H-benzimidazole-5-carboxylate." Acta Crystallographica Section C Crystal Structure Communications 69, no. 1 (December 13, 2012): 77–81. http://dx.doi.org/10.1107/s0108270112049669.

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In methyl 4-(4-chloroanilino)-3-nitrobenzoate, C14H11ClN2O4, (I), there is an intramolecular N—H...O hydrogen bond and the intramolecular distances provide evidence for electronic polarization of theo-quinonoid type. The molecules are linked into sheets built from N—H...O, C—H...O and C—H...π(arene) hydrogen bonds, together with an aromatic π–π stacking interaction. The molecules of methyl 1-benzyl-2-(4-chlorophenyl)-1H-benzimidazole-5-carboxylate, C22H17ClN2O2, (II), are also linked into sheets, this time by a combination of C—H...π(arene) hydrogen bonds and aromatic π–π stacking interactions.

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41

WATANABE, KAZUYUKI, TAKASHI ABE, TSUYOSHI OGINO, and SAKURA TAKEDA. "FIRST-PRINCIPLES STUDY ON ELECTRIC-FIELD-INDUCED STATES OF SILICON MICROCLUSTERS." Surface Review and Letters 03, no. 01 (February 1996): 389–93. http://dx.doi.org/10.1142/s0218625x9600070x.

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The first-principles molecular dynamics (FPMD) method is applied to a Si dimer and a Si trimer in electrostatic fields to calculate the charge polarization, the stable structures, and the cohesive energies. It is found that the bond length of the dimer increases, and the bond length and the bond angle of the trimer decrease as the electric field increases. The obtained structural change due to electric fields is compatible with the change in the cohesive energy. The vibrational dynamics of the dimer and trimer are also studied. The bond-bending mode of the trimer is found to be more largely influenced by the electric field than the bond-stretching mode. The present simulation revealed a fundamental role of electric fields in manipulating microclusters.

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42

Gadavanij, Savitri. "Contentious polities and political polarization in Thailand: Post-Thaksin reflections." Discourse & Society 31, no. 1 (December 16, 2019): 44–63. http://dx.doi.org/10.1177/0957926519877695.

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This article investigates the performance of identity and the concept of a ‘good’ leader reflected in the discourse of the former Prime Minister Thaksin Shinawatra, a controversial yet significant politician in Thai contemporary politics. The analysis focuses on how Thaksin constructed his political self, and how it redefined the Thai political field and the relevant practices. The article traces the discursive construction of his political identity in the radio program PM Thaksin talks to the people aired in 2001–2005. The findings indicate that Thaksin’s discourse constructed an ambivalent political identity through heterogeneity and dynamic use of ‘we’. Various mechanism of legitimization secured his popularity and created a lasting bond with the people. The discussion argues that while the discourse projecting a leadership style that is both confident and defiant strengthened the bond between Thaksin and his supporters, it increasingly pushed the ‘others’ away, leading to a growing ideological gap and later an adversarial sense among Thais, a fracture that still dominates the contemporary Thai political and social landscape.

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43

Vijayalakshmi, S., A. Föhlisch, P. S. Kirchmann, F. Hennies, A. Pietzsch, M. Nagasono, and W. Wurth. "Bond polarization and image-potential screening in adsorbed C6F6 on Cu(111)." Surface Science 600, no. 22 (November 2006): 4972–77. http://dx.doi.org/10.1016/j.susc.2006.08.017.

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44

Seidl, Peter Rudolf, Kátia Zaccur Leal, Valentim Emílio Uberti Costa, and Maria Elisabete Stapelbroek Mollmann. "Steric effects on carbon-13 NMR shifts: carbon-hydrogen bond polarization contributions." Magnetic Resonance in Chemistry 36, no. 4 (April 1998): 261–66. http://dx.doi.org/10.1002/(sici)1097-458x(199804)36:4<261::aid-omr261>3.0.co;2-1.

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45

Pawlik, Grzegorz, and Antoni C. Mitus. "Photoinduced Mass Transport in Azo-Polymers in 2D: Monte Carlo Study of Polarization Effects." Materials 13, no. 21 (October 22, 2020): 4724. http://dx.doi.org/10.3390/ma13214724.

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We studied the impact of light polarization on photoinduced dynamics of model azo-polymer chains in two dimensions, using bond-fluctuation Monte Carlo simulations. For two limiting models—sensitive to and independent of light polarization—their dynamics driven by photoisomerization of azo-dyes as well as by thermal effects was studied, including characterization of mass transport and chain reorientations. The corresponding schemes of light–matter interaction promote qualitatively different dynamics of photoinduced motion of azo-polymer chains. In particular, they can inhibit or trigger off a directed mass transport along a gradient of light illumination. The generic dynamics of single chains is superdiffusive and is promoted by breaking a symmetry present in the polarization independent model.

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46

Burck, Sebastian, Imre Hajdók, Martin Nieger, Denis Bubrin, Simon Schulze, Dietrich Gudat, and Dietrich Gudat. "Activation of Polarized Phosphorus–Phosphorus Bonds by Alkynes: Rational Synthesis of Unsymmetrical 1,2-Bisphosphine Ligands and Their Complexes." Zeitschrift für Naturforschung B 64, no. 1 (January 1, 2009): 63–72. http://dx.doi.org/10.1515/znb-2009-0109.

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The reactions of 1,1-diamino-2,2-diphenyl-substituted diphosphines featuring various degrees of P-P bond polarization with different alkynes were investigated. All diphosphines reacted with alkynes carrying one or two electron withdrawing carboxylic ester moieties under cleavage of the P-P bond and stereospecific phosphinyl-phosphination at the triple bond to give unsymmetrical ethane-1,2- bisphosphines. Several of the products were further converted into chelate complexes upon reaction with group-10 metal dihalides. All isolated compounds were characterized by analytical and spectroscopic data, and several of the new ligands and complexes by single-crystal X-ray diffraction studies.

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47

Starynowicz, Przemysław, and Tadeusz Lis. "Charge-density distribution in sodium bis(4-nitrophenyl)phosphate." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 70, no. 4 (July 31, 2014): 723–31. http://dx.doi.org/10.1107/s2052520614010439.

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The electron-density distribution in sodium bis(4-nitrophenyl)phosphate has been analyzed using the multipole refinement of X-ray diffraction data and of theoretical density-functional theory (DFT) calculations. The ester P—O bonds are particularly long and their topological parameters (density at the bond critical point, Laplacian) are lower than for other P—O bonds. Some disagreement between the experimental and theoretical charges of atoms constituting the nitro groups has been observed and the possible reasons are discussed. Weak polarization effects produced by sodium cations may be observed within the phosphate fragment; they are more manifest in the case of the nitro groups.

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48

Zhu, Changyan, Chaoxia Wen, Cong Wang, Min Zhang, Yun Geng, and Zhongmin Su. "Elongated heterometal double-sites promote nitrogen reduction on two-dimensional MM′B7 monolayers." Journal of Materials Chemistry A 9, no. 17 (2021): 10855–68. http://dx.doi.org/10.1039/d1ta01796a.

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Long-distance heterometal M and M′ metals can further promote the activation and polarization of the intrinsic triple bond due to an eligible orbital matching and a stronger accepting–donating interaction to the side-on adsorbed N₂ molecule.

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49

Selvaraju, Karuppannan, and Poomani Kumaradhas. "Charge Density Analysis and Transport Properties of TTF Based Molecular Nanowires: A DFT Approach." Journal of Nanoscience 2015 (March 4, 2015): 1–12. http://dx.doi.org/10.1155/2015/806181.

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The present study has been performed to understand the charge density distribution and the electrical characteristics of Au and thiol substituted tetrathiafulvalene (TTF) based molecular nanowire. A quantum chemical calculation has been carried out using DFT method (B3LYP) with the LANL2DZ basis set under various applied electric fields (EFs). The bond topological analysis characterizes the terminal Au–S and S–C bonds as well as all the bonds of central TTF unit of the molecule. The variation of electron density and Laplacian of electron density at the bond critical point of bonds for zero and different applied fields reveal the electron density distribution of the molecule. The molecular conformation, the variation of atomic charges and energy density distribution of the molecule have been analyzed for the various levels of applied EFs. The HOMO-LUMO gap calculated from quantum chemical calculations has been compared with the value calculated from the density of states. The variation of dipole moment due to the polarization effect and the I-V characteristics of the molecule for the various applied EFs have been well discussed.

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50

Huang, Wei, Yan Zhang, and J. Richard Sportsman. "A Fluorescence Polarization Assay for Cyclic Nucleotide Phosphodiesterases." Journal of Biomolecular Screening 7, no. 3 (June 2002): 215–22. http://dx.doi.org/10.1177/108705710200700305.

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Cyclic nucleotide phosphodiesterases (PDEs) catalyze the hydrolysis of the 3′-ester bond of cyclic AMP (cAMP) and cyclic GMP (cGMP), important second messengers in the transduction of a variety of extracellular signals. There is growing interest in the study of PDEs as drug targets for novel therapeutics. We describe the development of a homogeneous fluorescence polarization assay for PDEs based on the strong binding of PDE reaction products (i.e., AMP or GMP) onto modified nanoparticles through interactions with immobilized trivalent metal cations. This assay technology (IMAP) is applicable to both cAMP- and cGMP-specific PDEs. Results of the assay in 384- and 1536-well microplates are presented.

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